The present invention relates generally to the string-up of the leading portion of a continuous filament inline from a continuous forming process to a take-up device and specifically to the winder string-up of the leading portion of a continuous metal filament, particularly a glassy alloy strip, moving at high speed as it departs a moving quench surface in a high speed continuous casting process.
Glassy alloys are of considerable technological interest owing to their extraordinary physical properties as compared to the properties characterizing the polycrystalline form of such alloys. An overview of the nature of such materials and their properties are given in "Metallic Glasses", 28:5 Physics Today (1975) by J. J. Gilman. Representative examples are shown in U.S. Pat. No. 3,856,513 "Novel Amorphous Metals . . . " issued Dec. 24, 1974, to H. Chen and D. Polk, hereby incorporated by reference. The term "glassy alloy" is intended to refer to metals and alloys that are rapidly quenched from a liquid state to a substantially amorphous solid state, typically having less than about 50% crystallinity, and is considered to be synonymous with such terms as "amorphous metal alloy" and "metallic glass". Glassy alloys are well documented in the literature. For an extensive background see "Metallic Glasses", American Society For Metals (1978).
In the production of glassy alloy continuous filaments, typically an appropriate molten alloy is quenched at extreme quench rates, usually at least about 10.sup.6 .degree. C./sec., by extruding the molten alloy from a pressurized reservoir through an extrusion nozzle onto a high speed rotating quench surface, as is representatively shown in U.S. Pat. No. 4,142,571 for "Continuous Casting Method for Metallic Strips" issued Mar. 6, 1978, to M. Narasimhan, hereby incorporated by reference. Such filaments are necessarily thin, typically about 25 to 100 microns, owing to the extreme heat transfer requirements to prevent substantial crystallization, though considerable selectivity may be exercised respecting the transverse dimensions and cross-section of the filament. Thus, the term "filament" is intended to include strips, narrow and wide, as well as wire-like filaments.
It is commercially desirable to wind the filament inline with its casting process, as representatively shown in U.S. Pat. No. 3,938,583 "Apparatus For Production of Continuous Metal Filaments" issued Feb. 17, 1976, to S. Kavesh, hereby incorporated by reference. However, initiation of winding inline with the casting process is especially difficult for at least two reasons. First, linear casting speeds are high, typically 1,000 to 2,000 meters per minute (37 to 75 miles per hour). To string-up the filament inline from the casting process to a winder, the leading portion of the high speed filament must be captured as it departs the rotating quench surface and translated to the winder. String-up must be accomplished quickly and precisely, otherwise an entangled mass of filament accumulates rapidly. Secondly, the tension exerted on the filament during string-up must be maintained within limits. Tension must be sufficient to substantially dampen disrupting oscillations of the filament (excessive "flutter") but not so much as to disrupt the quenching operation.
It is conventional in high speed filament string-up to use an aspirator, whereby the leading portion of the moving filament is drawn through an aspirating nozzle for subsequent translation of the filament to the winder. There are several shortcomings of this method. First, the process usually must be done manually. Second, the noise level produced by such aspiration often exceeds 100 dB in the immediate vicinity. Third, there is a practical limit on the width of filaments that may be aspirated, probably about 8 to 10 centimeters for metallic filaments. Fourth, oscillations are induced in the filament by the turbulent flow through the aspirator.
These shortcomings of the conventional approach in stringing up a continuously formed filament directly from a high speed continuous casting process to an inline winder are overcome by the present invention, which provides for such string-up in a manner that is rapid, automatic, precise, and relatively quiet and that further permits filament tension control during string-up without complex feedback control.